Insulating casing condenser with horizontal stack



March 19, 1935. G. w. PlcKARD 1,994,533

` INsULA'rING cAsING coNDENsER WITH HORIZONTAL STACK Filed Nov. 24, 1951 4 Sheets-Sheet 1 Y 15 m. Il 15 l ATTORNEY March 19, 1935. G. w. PlcKARD INSULATING CASING CONDENSER WITH HORIZONTAL STACK 4 Sheets-Sheet 2 Filed NOV. 24, 1931 INVENToR GREENLEA w PacxARo BY www ATTORNEY March 19, 1935. G. w. PICKARD 1,994,533

' INSULTING CASING CONDENSER WITH HORIZONTAL STACK Filed Nov.. 24, 1951 4 Sheets-Sheet 3 4' INVENTOR GREENLEAF W P KARD BY ma,

ATTORNEY 19? 1935. G, w plcKARD INSULATING CASING CONDENSER WITH HORIZONTAL STACK 4 Sheets-Sheet 4 Filed Nov. l24, 1931 INVENTOR y GREENLEAF w. P1 mn BY zw@ fix/UW ATTORNEY l Patented Mar. 19, 1935 UNITED STATES PATENT oFFlcE INSULATING CASING CONDENSER WITH HORIZONTAL STACK This invention relates to improvements in elec- Greenleaf Whittier Pickard,

Newton Center,

Mass., assignor to Radio Corporation of AmerA ica, a. corporation of Delaware 16 Claims.

trical condensers of the insulating casing type which is particularly radapted for high tension service in a short wave or ultra high frequency 5 circuit, and more particularly to condensers of the mica sheet stack type.

An object of thishkinvention is to simplify and improve the construction of an insulating casing condenser.

Another object of this invention is to reduce the amount of metal employed in the construction of insulating casing condensers and thereby decrease the eddy current losses.

Another object is to provide a condenser arrangement Whereby the stack pressure screws protrude from the sides of the insulating casing, and serve the dual purpose of compressing the mica and foils of the condenser stack and act as a high tension electric terminal.

A feature of this invention is the rounding over of the bearing blocks at the points where they contact with the inside walls of the insulating casing, to substantially increase the electric creepage path, and prevent any brush discharge to the adjacent metal parts of the opposite potential.

Another object of this invention is to provide for the slotting and rounding over of therme- .tallic end members and also those of 4other metallic members of any substantial cross section to prevent any short circuiting turn effect when the condenser is placed in the field of high frequency circuit.

Another feature of this invention is that the condenser stack is retained under pressure by a novel means which causes the pressure to be exerted on the side walls of the casing, the strain on the insulating casing walls being part in tension and part in compression.

I have found that when high tension condensers of the ordinary typel are used in an ultra high frequency circuit, eddy currents are set up in the metal, and such currents result in electrical or heat losses and thereby decrease the overall eiliciency ofthe condenser.

In order to accomplish the purpose of this' invention I provide a structure which is an 'improvement over prior insulating casing condensers, such as Proctor Patent 1,660,937, wherein the stack axis is placed in a vertical plane parallel with the axis of the casing. According to one aspect of my invention, the stack axis is placed in a horizontal plane, a position which is at right angles with respect to the axis of the casing.

I, furthermore, retain only suflicient metal to provide a rugged structure with suitable mounting and electric connections. I further provide an air gap in the rim to prevent any tendency of any short circuiting turn effect. I also prevent brushing at the ultra high frequencies by rounding over the metal at all points within the field.

The material and shape of the insulating casing are such that it is slightly resilient and has a take-up of pressure after there has been a tendency to distort the casing from that of a true circle. I have also found with this new and improved way of compressing the stack that I am able to make the metallic end or rim members identical in size and shape, thus reducing the cost of manufacture.

'I'he invention consists of the various features of the construction as described and as illustrated in the accompanying drawings showing several embodiments. In the drawings, like reference characters refer to like parts, of Which- Fig. l is a plan view partly in section, the section being 'taken on lines 2--2 of Fig. 2;

Fig. 2 is a vertical cross section of Fig. 1, the section being taken at lines 11;

Fig. 3 is also a vertical cross section showing a modified form of obtaining a clamping pressure on the stack by means of a threaded metallic bushing inserted within the casing; i

Fig. 4 is a vertical cross section of a further modified form similar to that of Fig. 3;

Fig. 5, like that of Fig. 4, is a vertical cross section of a casing similar to that of Fig. 3, but shows a further modified form;

Fig. 6 is a vertical cross section of an insulating casing condenser similar to that of Figs. 3 and 4 and shows further modification of a stack arrangement;

Figs. 7 and 8 illustrate certain details of the condenser construction;

Fig. 9 is a plan view partly in section of a modified form of this invention, the section being taken on lines 4 4 of Fig. 10;

Fig. 10 is a vertical 'cross section of Fig. 9,y

the section being taken on lines 3-3 of Fig. 9\.

The general structure of the simplified and improved condenser is best shown in Fig. 2 wherein the insulating casing 1 is of Pyrex glass or Isolantite, or other good insulating material of low dielectric loss, in the form of a tube or cylinder. Surrounding the sides of the stack 2 at each end of the insulating casing and resting on the edge thereof, there is an annular metallic rim or end mounting member indicated generally as 3 and 4, which is preferably of aluminum, fastened either the top and bottom metallic rim. There are also provided mounting lugs 25 having openings therein for the mounting of the condenser. The metallic mounting members 3 and 4 are slotted at 26 to overcome any short circuited turn effect;V

likewise all edges are completely rounded over at points 27, to further reduce any tendency of brush discharge or corona loss when the condenser is placed within the field of a high frequency circuit.

'I'he bottom and top of the condenser is closed by insulating discs 6 and 7, preferably of Pyrex glass, Bakelite, Dilecto, or any other good insulating material of low dielectric loss. These insulating elements 6 and 7 closely fit the recesses 3' and 4 in the metallic members, and are provided with a bevelled edge.

In assembling the condenser the insulating casing is cemented to metallic members 3 and 4. 'I'he series sectional mica and foil stack which has been previously assembled is then placed in the central area of the casing with conducting strips 12 and 13 at opposite ends forming terminals thereof, and is secured in place by means of a bearing plate or block 8 which is rounded over at points 9 to increase the'electrical creepage path, and further recessed at a point 9a to reduce its metallic mass. Pressure is obtained by means of tapered blocks or wedges 10 and 11. When the proper alignment and pressure is obtained the extensions of the conducting strips 12 and 13, which are strips of copper about as wide as the stack, are fastened respectively-to the metallic members 3 and 4 by means of screws 14 and 15. To secure good electrical and thermal conductivity, solder is flowed in at points 16 and 17. The bottom is then closed by securing the insulating plate 7 to the metallic rim 4 for example by rolling over or burring the rim over the edge of the disc at a. point 18, or fastening by other suitable securing means such as cement.

'Ihe condenser is then filled with molten insulating material 19 such as parailii'ie wax or other good insulating embedment material to a. proper level indicated at 20; then in a like manner as described above, the insulating disc 6 is fastened to the metallic member or annular rim 3. The completed condenser is then given the proper tests, such as voltage and heat running tests. y

In Fig. 3 the construction is similar to that of Fig. 2 except that the blocks or wedges 10 and l1 are replaced by a metallic pressure plate 21 with a narrow vertical slot indicated at 21', a metallic bushing 22, which is threaded to receive a bolt 23 by means of which the pressure on the stack 2 is varied until proper pressure is secured on the active area of the stack to keep the foil in intimate contact with the mica which results in keeping the capacity of the condenser practically constant. The inside of the casing 1 is flattened at 1 to i properly seat the metallic bushing 22. After the condenser is filled, sealed up and tested as described above, the head of the pressure bolt 23 is cut off at a point 24.

Fig. 4 is a cross section showing an insulating casing condenser similar to that of Fig. 3 except that the condenser stack 27 is here divided in the center at 28, a pair of terminals 13'-13 disposed at opposite ends of the stack. are fastened to the rim 3, while a lead 29 from the mid-point of the stack is fastened to the rim 4.

The modified form of Fig. 5 shows a similar casing to that of Fig. 3 except that herein is shown a pair of parallel arranged condenser stacks 30 and 3l disposed one above the other with terminals 32 and 33 projecting through the insulating casing with suitable nuts 34 and washers 35 so that an external connection can be made to obtainthe capacity of one stack or both stacks in series, or parallel connection of both stacks by making proper external connections to the terminals 32 and 33 mentioned above. Likewise, the bearing plate 36 is enlarged to provide sumcient bearing for this double stack arrangement.

The modified form shown in Fig. 6 is that of an insulating casing condenser similar to that of Figs. 3 and 4 except that a plurality of stacks 38,

39 and 40 disposed one above the other, are connected by wide copper strips 41 and 42 in a series arrangement. By means of projecting terminals 32 the capacity of a single stack or any series combination of more than one, may be obtained by making suitable external connections.

Fig. 7 is a detailed section of the improved bearing plate to illustrate more fully the method of which is employed to reduce the eddy current loss of the metallic members within the condenser field. It is to be noted that there is a complete rounding over of all the edges at corners such as 43, 44, 45, 46, 47, 48, 49 and 58 to reduce the eddy current losses.

Fig. 8 is a plan view of Fig. 7 and shows the rounding over of edges 51 and 52 and the construction of the slot tov reduce the eddy current losses.

In the modified form of condenser shown in Figs. 9 and l0, the rims 3 and 4 of the prior modifications are replaced by the end elements 53 and 54 shaped to a funnel-like configuration so as to act as the armatures or plates of a condenser of the xed capacity type having an air of solid dielectric. In the latter case the space between the cylinders 53 and 54 are filled with molten sulphur 55, or any other good dielectric material. This modied form may also be manufactured as a vacuum condenser by properly sealing the slots 56 and 57 with glass or any good cement of low dielectric loss and exhausting the air within the casing, the seal-oil being located at 58 or any other convenient point. l

Although this invention has been described as embodied in a particular form or arrangement of parts, it should be understood that it is capable of embodiment in other and different forms within the spirit and scope of the appended claims.

What I claim is:

l. In electric condensers, an insulating casing open at opposite ends, ring-like metallic current conducting and mounting members surrounding the ends of the insulating casing, said members having an inside diameter greater than the inside diameter of said casing, and two insulating discs for closing both of said ends.

2. In electric condensers, an insulating casing open at opposite ends, ring-like metallic current conducting and mounting members surrounding the ends of the insulating casing, each of said opposite ends being closed with insulated discs having a bevelled edge over which the inner periphery of said mounting members extend to retain said discs in place.

3. In a condenser for high tension service comprising an insulating casing, metallic end members fixed to the casing for suporting said casing,

said members being slotted to reduce eddy current losses and insulating members for sealing the ends of the casing.

4. In a high tension condenser comprising a tubular insulating casing, metallic ring-like end members located at each end of said casing, insuiating elements secured by the inner periphery of said ring-like end members for closing the ends ofthe casing, a horizontal series section stack within the casing, said stack axis being at right angles to the axis of said casing, and a bearing plate for said stack, the periphery of said bearing plate being rounded over to increase the electrical creepage -path from the said horizontal stack to the metallic end members.

5. In a condenser for high frequency service comprising an insulating casing, a condenser stack within the casing, metallic members fixed to the casing, said members being slotted to reduce eddy current losses.

6. In a high tension condenser comprising a tubular insulating casing, metallic ring-like end members and insulating discs closing the ends of the casing, said insulating discs having a bevelled edge over which the inner periphery of said ringlike end members extend to retain said discs in place, a horizontal series section condenser stack within the casing, said stack axis being at right angles to the axis of said casing, and clamping means for said stack whereby the casing is both under tension and under compression.

7. In a short wave condenser o the high tension type, comprising an insulating casing, metallic ring-like current conducting and mounting end members and insulating discs closing the ends of the casing, said insulating discs having a bevelled edge over which theinner periphery of said metallic conducting and mounting members extend to retain said discs in place. a plurality of horizontal stacks within `the walls of the casing, and a plurality of threaded bushings having a ange and a screw cooperating with each of said bushings to retain each one of the said stacks under compression.

8. An insulating casing condenser comprising a tubular insulating casing, two ring-like metallic members each having an air gap therein surrounding the ends of the insulating casing, a stack within said casing, and a threaded metallic bushing having a flange, said bushing being projected through the sides of the casing and a screw cooperating with said bushing for compressing said stack..

9. In an electric condenser of the high tension type, an insulating casing, ring-like metallic members having air gaps therein surrounding the opposite ends of said insulating casing, insulated discs for closing said opposite ends, a. stack within the Walls of the casing, and a pair of slotted Wedges for compressing said stack.

10. An insulating casing condenser comprising an insulating casing, metallic current conducting and mounting members secured to the ends of the and mounting members each having a radial slot Vforming a gap, said members secured to the ends of the insulating casing, one of said members forming an armature of the condenser, the opposite armature being formed by the other said metallic member, and a dielectric of sulphur interposed between said armatures.

l2. An insulating casing condenser comprising an insulating casing, metallic current conducting and mounting members having a radial slot forming a gap, said members secured to the ends of the insulating casing, one of said members forming an armature of the condenser, the opposite armature being formed by the other said metallic member, and an insulating cover secured to the inner periphery of each of said current conducting and mounting members, the space enclosed by said casing being evacuated.

13. In combination a tubular insulating casing, a ring-like current conducting and mounting member surrounding each end of said casing, discs of insulating material for closing the ends of said casing, a plurality of horizontal stacks within said casing, said stacks having axes at right angles to the axis of said casing, and a corresponding number of stack clamping and terminal connection means each comprising a metallic bushing having a flange, an internal thread fora terminal stud.` said bushing projecting through the walls of said insulating casing.

14. In a high tension electric condenser a tubular insulating casing, a metallic ring-like current conducting and mounting member located at each end of said casing, insulating discs for closing the ends of said casing, a horizontal condenser stack with axis positioned at right angles to the axis of said casing, said stack positioned within said casing, and means for compressing the stack within the casing walls.

15. In a high tension condenser a tubular n- 4 sulating casing, two metallic ring-likecurrent conducting and mounting members having a radial slot forming a gap and surrounding the ends of said casing, a horizontal condenser Steck within the casing with axis positioned at right angles to the axis of said casing, and means for compressing the stack within the condenser walls.

16. In electric condensers a tubular insulating casing open at opposite ends, current conducting and mounting members located at each end of said casing, comprising peripheral ring-like metallic members fastened to said casing, and a disc of insulating material secured by the inner periphery of each of said ring-like metallic members.

GREENLEAF WHITTIER PICKARD. 

